Tweak Sequence.all() and Sequence.any().

When possible, they return the actual value from the predicate
instead of always just "true" and "false". This matches && and ||
which evaluate to the RHS or LHS when appropriate.

test/core/sequence/all.wren

@@ -0,0 +1,10 @@
+var a = [1, 2, 3]
+IO.print(a.all {|x| x > 1 }) // expect: false
+IO.print(a.all {|x| x > 0 }) // expect: true
+IO.print([].all {|x| false }) // expect: true
+
+// Returns first falsey value.
+IO.print(a.all {|x| x < 2 ? null : false }) // expect: null
+
+// Returns last truthy value.
+IO.print(a.all {|x| x }) // expect: 3